1. Field of the Invention
The present invention relates to an image encoding apparatus and a method of controlling the same.
2. Description of the Related Art
Image data with a high resolution and a wide color gamut has an enormous data size and also requires high memory cost and long time for image processing or data transfer. This makes data handling difficult. To solve this problem, a method has conventionally been proposed which holds, for a plurality of pixels, one piece of color information and information representing the arrangement of the color, thereby converting an original resolution image into data in a smaller size (e.g., Japanese Patent Laid-Open No. 2001-313834).
Another method has also been proposed which separates image data into text image portions and photo image portions and generates reduced images thereof. These pieces of information are held. To restore the original resolution image, restoration target pixels are predicted and restored based on the pixels of a reduced image of interest and their neighboring pixels (e.g., Japanese Patent Laid-Open No. 10-173913).
In a method of generating interpolation data as well as reduced images generated by resolution conversion, the interpolation data requires at least color information and arrangement information for color arrangement to reproduce the original resolution image. To do this, at least one piece of arrangement information needs to be held for one pixel of the original resolution image. Hence, the effect of decreasing the code amount of the interpolation data is limited to 1/(data amount of one pixel).
In a method of interpolating a restoration target image based on a predetermined rule without generating interpolation data, data to be interpolated is only an estimated value. For this reason, it is impossible to losslessly reproduce the original resolution image.